“You have to impose unity and relate the parts of a décor, even the minor parts, to the whole,” explains architect Peter Marino. He entirely reenvisioned a prewar apartment for a Manhattan couple, turning it into a coherent residence filled with important art and antiques. In the living room, Marino hung Intablature, 1975, by Roy Lichtenstein, left, and a 1983 work by Jean-Michel Basquiat.